The long-term objectives of this proposal are to understand the genetic and neurobiological basis of individual differences in socio-communicative behavior and cognition in the chimpanzee, a potential valuable species for modeling aspects of the autism phenotype. One aim of the proposed studies is to behavioral characterize a relatively large sample of chimpanzees (N = 290) on their ability to initiate and engage in joint attention during interspecies communication as assessed on two structured tasks. In addition, measures of sociality and communication will be evaluated during interspecies interaction using observational methods. In addition to the behavioral measures, DNA samples will be obtained from each chimpanzees and allele frequencies and assessment of polymorphic variation in the AVPR1A (vasopressin) and OXTR (oxytocin) genes. The variation in performance on the behavioral measures will be correlated with polymorphic variation in these genes as well as in relation to non-genetic factors including sex and early rearing history of the subjects. These analyses will provide valuable information on the role of genetic and non-genetic factors on individual differences in socio-communicative competencies. In vivo magnetic resonance images will also be collected in a subset of the chimpanzee sample. From the MRI, subjects with different genotypes for the AVPR1A and OXTR gene will be compared on grey and white matter integrity using whole brain, voxel-based morphometry (VBM). This analysis will provide critical data on the role of these genes on the development organization of grey and white matter integrity. In addition, based on the VBM analysis, brain regions of interest that distinguish different genotypes will be quantified and subsequently applied to individual MRI scans. The individual MRI measures will then be correlated with the behavioral phenotypes to examine whether the brain regions distinguishing different AVPR1A and OXTR genotypes subsequently explain variation in socio-communicative competencies. The collective studies will contribute to our understanding of genetic and non-genetic factors that influence cortical organization and socio-communicative competencies.